One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,6)(3,7,8,5)(9,10,12,18,14,17,13,15)(11,19,20,16,22,23,21,24)(1,3,4,8)(2,5,6,7)(10,15)(12,13)(16,23)(17,18)(19,24)(20,21)(25,26)(27,34)(28,32)(29,37)(30,33)(31,35)(36,39)(38,40)(9,11,14,22)(10,16,17,24)(12,21,13,20)(15,23,18,19)(25,27)(26,31)(28,35)(29,38)(30,36)(32,39)(33,40)(34,37)(10,17)(15,18)(16,24)(19,23)(25,28,30,29)(26,32,33,37)(27,35,36,38)(31,39,40,34)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.